It follows the life of William H. Bonney aka Billy the Kid (played by Emilio Estevez) in the years following the Lincoln County War in which Billy was part of "The Regulators" — a group of around 6 highly skilled gunmen avenging the death of John Tunstall — and the years before Billy's documented death. The film, however, is told by Brushy Bill Roberts, a man who in the 1940s appeared claiming to be the real Billy the Kid.

While the film is not entirely historically accurate, it does show some of the key events leading up to Billy's documented death, including his talks with Governor Lew Wallace, his capture by friend-turned-foe Pat Garrett, his trial and his subsequent escape in which he killed two deputies.